Nginx and uploads

This seems odd. If it wasn't meant for Nginx to process uploaded files, then
it couldn't have processed them by itself.
For example, I changed
location @test {
proxy_pass http://example.com:8080;
to
location @test {
default_type text/html;
root /www;
and removed the :8080 server part and it still works.
So I am inclined to think that there must be a way to set the filename
without going to such lenghts as to change the code.
Posted at Nginx Forum: http://forum.nginx.org/read.php?2,230184,230212#msg-230212